// reuse/Wind.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Inheritance & upcasting

class Instrument {
    public void play() {
    }

    static void tune(Instrument i) {
        // ...
        i.play();
    }
}

// Wind objects are instruments
// because they have the same interface:
public class Wind extends Instrument {
    public static void main(String[] args) {
        Wind flute = new Wind();
        Instrument.tune(flute); // Upcasting
    }
}
